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bitarray.h

00001 //
00002 // bitarray.h
00003 //
00004 // Modifications are
00005 // Copyright (C) 1996 Limit Point Systems, Inc.
00006 //
00007 // Author: Edward Seidl <seidl@janed.com>
00008 // Maintainer: LPS
00009 //
00010 // This file is part of the SC Toolkit.
00011 //
00012 // The SC Toolkit is free software; you can redistribute it and/or modify
00013 // it under the terms of the GNU Library General Public License as published by
00014 // the Free Software Foundation; either version 2, or (at your option)
00015 // any later version.
00016 //
00017 // The SC Toolkit is distributed in the hope that it will be useful,
00018 // but WITHOUT ANY WARRANTY; without even the implied warranty of
00019 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
00020 // GNU Library General Public License for more details.
00021 //
00022 // You should have received a copy of the GNU Library General Public License
00023 // along with the SC Toolkit; see the file COPYING.LIB.  If not, write to
00024 // the Free Software Foundation, 675 Mass Ave, Cambridge, MA 02139, USA.
00025 //
00026 // The U.S. Government is granted a limited license as per AL 91-7.
00027 //
00028 
00029 /* bitarray.h -- definition of the BitArray Class
00030  *
00031  *      THIS SOFTWARE FITS THE DESCRIPTION IN THE U.S. COPYRIGHT ACT OF A
00032  *      "UNITED STATES GOVERNMENT WORK".  IT WAS WRITTEN AS A PART OF THE
00033  *      AUTHOR'S OFFICIAL DUTIES AS A GOVERNMENT EMPLOYEE.  THIS MEANS IT
00034  *      CANNOT BE COPYRIGHTED.  THIS SOFTWARE IS FREELY AVAILABLE TO THE
00035  *      PUBLIC FOR USE WITHOUT A COPYRIGHT NOTICE, AND THERE ARE NO
00036  *      RESTRICTIONS ON ITS USE, NOW OR SUBSEQUENTLY.
00037  *
00038  *  Author:
00039  *      E. T. Seidl
00040  *      Bldg. 12A, Rm. 2033
00041  *      Computer Systems Laboratory
00042  *      Division of Computer Research and Technology
00043  *      National Institutes of Health
00044  *      Bethesda, Maryland 20892
00045  *      Internet: seidl@alw.nih.gov
00046  *      July, 1993
00047  */
00048 
00049 #ifndef _util_container_bitarray_h
00050 #define _util_container_bitarray_h
00051 
00052 #include <string.h>
00053 #include <stdlib.h>
00054 
00055 #include <util/misc/formio.h>
00056 
00057 namespace sc {
00058 
00059 //
00060 // class BitArrayLTri is used as the lower triangle of a boolean matrix.
00061 // rather than storing an int or a char, just use one bit for each, so
00062 // instead of n(n+1)/2 bytes of storage you have n(n+1)/16 bytes.  A
00063 // further savings of n bits could be obtained by setting the diagonal to
00064 // always true or always false depending on the application, but this would
00065 // probably be more expensive computationally than it's worth.
00066 //
00067 
00068 class BitArrayLTri {
00069   private:
00070     unsigned char *a;
00071     int n;
00072     int nm;
00073     int na;
00074 
00075     static int
00076     ij_offset(int i, int j)
00077         {
00078           return (i>j) ? (((i*(i+1)) >> 1) + j) : (((j*(j+1)) >> 1) + i);
00079         }
00080 
00081   public:
00082     BitArrayLTri(int =0, int =0);
00083     ~BitArrayLTri();
00084 
00085     void set(unsigned int i) { a[(i>>3)] |= (1 << (i&7)); }
00086     void set(unsigned int i, unsigned int j) { set(ij_offset(i,j)); }
00087 
00088     int is_set(unsigned int i, unsigned int j) const
00089       { int ij = ij_offset(i,j); return (a[(ij>>3)] & (1 << (ij&7))); }
00090     int is_set(unsigned int i) const
00091       { return (a[(i>>3)] & (1 << (i&7))); }
00092 
00093     int operator()(unsigned int i, unsigned int j) const
00094       { int ij = ij_offset(i,j); return (a[(ij>>3)] & (1 << (ij&7))); }
00095     int operator()(unsigned int i) const
00096       { return (a[(i>>3)] & (1 << (i&7))); }
00097     int operator[](unsigned int i) const
00098       { return (a[(i>>3)] & (1 << (i&7))); }
00099 
00100     int dim() const { return na; }
00101     int nrow() const { return nm; }
00102     int ncol() const { return nm; }
00103 
00104     int degree(unsigned int i) const {
00105       int nedge=0;
00106       for (int j=0; j < nm; j++) if ((*this)(i,j)) nedge++;
00107       return nedge;
00108     }
00109 };
00110 
00111 }
00112 
00113 #endif
00114 
00115 // Local Variables:
00116 // mode: c++
00117 // c-file-style: "ETS"
00118 // End:

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